gc: diagnose unused labels

R=ken2
CC=golang-dev
https://golang.org/cl/4287047

1 files changed, 85 insertions, 0 deletions

diff --git a/test/label1.go b/test/label1.go
new file mode 100644
index 0000000000..bba63f23d2
--- /dev/null
+++ b/test/label1.go
@@ -0,0 +1,85 @@
+// errchk $G -e $D/$F.go
+
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Pass 2 label errors.
+
+package main
+
+var x int
+
+func f() {
+L1:
+	for {
+		if x == 0 {
+			break L1
+		}
+		if x == 1 {
+			continue L1
+		}
+		goto L1
+	}
+
+L2:
+	select {
+	default:
+		if x == 0 {
+			break L2
+		}
+		if x == 1 {
+			continue L2 // ERROR "invalid continue label L2"
+		}
+		goto L2
+	}
+
+L3:
+	switch {
+	case x > 10:
+		if x == 11 {
+			break L3
+		}
+		if x == 12 {
+			continue L3 // ERROR "invalid continue label L3"
+		}
+		goto L3
+	}
+
+L4:
+	if true {
+		if x == 13 {
+			break L4 // ERROR "invalid break label L4"
+		}
+		if x == 14 {
+			continue L4 // ERROR "invalid continue label L4"
+		}
+		if x == 15 {
+			goto L4
+		}
+	}
+
+L5:
+	f()
+	if x == 16 {
+		break L5 // ERROR "invalid break label L5"
+	}
+	if x == 17 {
+		continue L5 // ERROR "invalid continue label L5"
+	}
+	if x == 18 {
+		goto L5
+	}
+
+	for {
+		if x == 19 {
+			break L1 // ERROR "invalid break label L1"
+		}
+		if x == 20 {
+			continue L1 // ERROR "invalid continue label L1"
+		}
+		if x == 21 {
+			goto L1
+		}
+	}
+}